This invention relates to a high-frequency shielding case of a semiconductor laser apparatus.
It has been widely known that a high-frequency oscillation circuit for semiconductor laser has to be stored in a high-frequency shielding case for shielding an electromagnetic wave generated therefrom. It is desirable that a mounting of a high-frequency shielding case on a substrate on which a high-frequency oscillation circuit is formed be readily made and that the high-frequency shielding case be made as small as possible with a highest possible rigidity.
In an optical head apparatus disclosed, for example, in Jpn. UM. Appl. KOKOKU Publication NO. 7-20935, a high-frequency shielding case for a semiconductor laser device comprises a heat radiator plate overlaid on a bottom surface of a laser diode and having an opening into which a terminal of the laser diode is inserted; a first high-frequency shielding case half overlaid on the heat radiator plate at a side opposite to the laser diode and having an opening into which the terminal of the laser diode having been inserted into the opening of the heat radiation plate is inserted; and a second high-frequency shielding case half fitted on the first high frequency shielding case half, from the side opposite to the heat radiator plate, overlaying a peripheral portion thereof onto a peripheral portion of the first high-frequency shielding case half, and being soldered the peripheral portion to the heat radiator plate, and wherein a high-frequency oscillation circuit board for the laser diode is electrically connected to the terminal of the laser diode, the terminal projecting from the opening, while the circuit board abuts against the peripheral portion of the opening in an inner surface of the first high-frequency shielding case half.
In the high-frequency shielding case of this conventional semiconductor laser apparatus, since the peripheral portion of the second high-frequency shielding case half is directly soldered to the heat radiator plate and heat used for soldering is radiated by the heat radiator plate, lots of heat as well as of time are needed for soldering. Therefore, quantity of heat transmitted from the heat radiator plate to the laser diode becomes large during the soldering operation and, in the soldering operation, a temperature of the laser diode is increased, thus sometimes deteriorating a reliability of the laser diode.
The present invention is derived from this situation and an object of the present invention is to provide a high frequency shielding case of a semiconductor laser apparatus which can decrease heat and time required for soldering to fix a high-frequency shielding case, and hence easier a soldering operation, and can prevent a lowering in a reliability of a laser diode caused by heat generated in a soldering operation.